JPS5934460B2 - Resin model for microwave heating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a model for forming a casting mold which is hardened by microwave heating.

Traditionally, the models used in various molding methods have mainly been wooden molds and metal molds.

However, in recent years, as microwave heating devices have become popular as household microwave ovens, they have become cheaper, and attempts have been made to improve molding speed by applying them to various molding methods, but wooden molds and metal molds It has become clear that the method cannot be used due to the following drawbacks. In other words, wooden molds have a large dielectric constant and loss coefficient, and have the disadvantage of absorbing microwaves and overheating and deforming.Molds have the property of reflecting microwaves, and microwaves can reach the molding sand in the mold. There was a drawback that it could not be heated because it could not reach the target temperature. In order to provide a model that does not have such defects during microwave heating, the inventors of the present invention have conducted repeated research. By adding microscopic hollow bodies of inorganic or organic matter to the resin, the resin is made porous. The present invention was achieved by discovering that the above object could be achieved by using the material as the internal material of the model.

The accompanying drawing is a longitudinal sectional view showing a model of the present invention. In the figure, 1 indicates a porous resin model, and 2 indicates its surface coating layer. Base resins for foamed resin models include polyester resins, polyurethane resins,
There are silicone resins, polystyrene resins, epoxy resins, polyimide resins, phenolic resins, acrylic resins, etc. These resins are made by adding micro hollow bodies (described later) and pouring them into a mold with a predetermined shape. Leave at room temperature or heat to condense.

In addition, injection molding, extrusion molding, transfer molding, etc.
In order to obtain a predetermined shape or material, in addition to the above-mentioned casting resin, micro-hollows can be used in polypropylene, polyethylene, fluororesin, cellulose derivatives, urea resin, melamine resin, aniline resin, xylene resin, diallyl resin, etc. Add body and shape. Next, we will discuss micro hollow bodies.

Microhollow bodies are single-cell hollow spheres with an outer diameter on the order of microns and consisting of thin septa.

The types are broadly classified into inorganic materials, organic materials, and metals, and in the present invention, inorganic materials and organic materials are used. Inorganic substances include alumina, silica, zirconia, magnesia,
There are glass, shirasu, fly ash, carbon, sodium silicate, etc. Organic substances include epoxy resin,
Examples include polyurethane, saran, polystyrene, phenolic resin, and polyamide. Next, the surface coating layer 2 will be explained.

This surface coating layer 2 is not essential and may be provided as appropriate. As the surface coating layer, solvent-based or non-solvent-based varnishes and paints are used. Those belonging to the former include shellac, oil-based asphalt, phenolic resin, alkyd, epoxy, diphenyl ether, and silicone.
Those belonging to the latter include polyester, epoxy, urethane, silicone, and polyimide. The coating method is generally performed by spray coating or impregnation coating. Application examples of the present invention will be described below.

Table 1 shows typical formulations, and the details will be described below.

Example This example is a resin model using epoxy resin as the base resin and making it porous using Shirasu balloons.

It has very good heat resistance. Epoxy resin 1
00 parts is heated to around 60° C., and 75 parts of a curing agent are mixed therein. To this, 15 parts of Shirasu Balloon (trade name) is added as a micro hollow body. This mixture is poured into a plaster mold with a predetermined shape and kept at around 80°C to gel. After gelation, a porous resin having an apparent specific gravity of 0.85 g/Crlt is obtained by further heating at around 200° C. for about 16 hours. The surface of the porous resin obtained had excellent stability and no surface coating was required. The effects of the resin model of the present invention described above are particularly remarkable when used for core removal.

In other words, unlike wooden molds and molds, the molding material is resin or inorganic material with a low dielectric loss coefficient, and the inside is porous due to micro hollow bodies, so compared to conventional resin models with solid insides. The rise in mold temperature due to microwave irradiation is reduced in proportion to the specific gravity of the resin model. Therefore, it is possible to harden the molding sand by irradiating it with microwaves while the mold is filled with molding sand, which is difficult to do with wooden molds or metal molds.Moreover, the loss of microwave energy is lower than that of resin models with solid interiors. Because it is less, more energy is absorbed by the foundry sand (binder), which quickly generates heat and hardens. Furthermore, since the model of the present invention absorbs less energy than a resin model having a solid interior, it has the advantage that the model is less likely to crack or deform due to an increase in mold temperature. In addition, the parts in contact with the model are
Due to the excellent insulation effect of the model, there is little heat loss and the foundry sand is heated evenly. Other effects include improved workability, reduced model costs and weight by saving resin, and improved mechanical properties such as vibration and shock absorption.

[Brief explanation of the drawing]

The attached figure shows a cross section of an embodiment of the model according to the invention.

Claims (1)

[Claims] 1. A resin model for microwave heating, characterized in that the resin is made porous by adding microscopic hollow bodies of an inorganic or organic substance to the resin, and has this porous resin as an internal structure.